Labor and Milking Machine Inputs to Milk Harvest in Dairy Cattle: Implications for Direct Selection

Abstract

Components of variance, repeatabilities, and correlations among milking labor and machine inputs, flow rate, and yield characters were derived from data on lactating Holstein and Jersey cows and provided the basis for determining efficacy of direct selection for improved milking economy. Intralactation variance components for cow were 324, 121, and 7657s2/milking for total labor inputs, machine stripping, and actual machine time for Holsteins. Intralactation estimates were larger than estimates among lactations. Machine stripping was the primary component of total labor input that varied among cows. Intralactation repeat-abilities for total labor inputs, machine stripping, and actual machine input for Holsteins were .29, .20, and .42. The partial correlation of average flow rate with total labor inputs holding milk yield constant was —.56, exceeding that with peak rate. Elimination of machine stripping and minimizing overmilking appeared the best means of reducing average cost of milk harvest. Culling of cows exhibiting unsuitable demands for labor and machine inputs is a more appropriate strategy for improvement than direct selection for efficiency of milking labor.